Arrangement for removing the deposit from the tubular systems of steam generators with forced passage of the operating medium



March 3, 1936. M. EULE 2,032,924

ARRANGEMENT FOR REMOVING THE DEPOSIT FROM THE TUBULAR SYSTEMS OF STEAM GENERATORS WITH FORCED PASSAGE O THE OPERATING MEDIUM Filed March 1, 1934 2 Sheets-Sheet l WITNESSES 1 INVENTOR d Mnn'rm EULE pwmwfif BY WM l (bl M ATTORNEY March 3, 1936. M. EULE 2,032,924

ARRANGEMENT FOR REMOVING THE DEPOSIT FROM THE TUBULAR SYSTEMS OF STEAM GENERATORS WITH FORCED PASSAGE OF THE OPERATING MEDIUM Filed March 1, 1954 2 sheets-sheet 2 FIGMZ. $4

INVENTOR' FIG. 70. F) 6,11. MARTIN Eu:

BY a. 0'5. M

ATTORN EY Patented Mar. 3, 1936 UNITED STATES PATENT OFFICE Martin Eule, Berlin- Spandau, Germany, assignor to Siemens-Schuckertwerke Aktiengesellschaft, Berlin-Siemensstadt, Germany, a corporation of Germany Application March 1, 1934, Serial No. 713,445 In Germany February 6, 1933 8 Claims. (01. 122-379) My invention relates to steam generators of the forced-flow type and it has for an object to provide apparatus of this character with means for effecting the removal of salt deposits therefrom.

With boilers of the drum type, salts entrained with the feed water ordinarily deposit within the drum and such deposits are ordinarily removed by blow-down operations. On the other hand, with a forced-flow boiler, the nature of the construction does not permit of such localized salt deposition nor that method of removal, the salt being deposited along the inner walls of the tube portions over a substantial length of the latter. Hence, it is essential to provide salt removal means which is essentially different in structure, relation and operation when com.- pared to blow-down apparatus used with drum type boilers.

It has heretofore been proposed to provide the tubular portions of the evaporation or salt deposit zone of a forced-flow boiler with outlet conduits which could be opened to effect the removal of salt deposits, together with means for increasing the operating medium pressure at the point of removal when an outlet conduit is opened. The rise in pressure necessarily increases the temperature of vaporization with the result that operating medium in the liquid state flows through the salt deposit zone and is discharged through an open outlet conduit, salt being dissolved and entrained by the liquid operating medium. Each of the tubular portions of the salt deposit zone of a boiler may be cleaned, one by one, in this manner. This arrangement is objectionable because of the quantity of operating medium required to flow through the outlet conduit in order to effect cleaning of a tubular portion, for the quantity of water so discharged may be so large as to substantially impair the operation of the generator, particularly as the storage capacity of a boiler of this type is relatively small. Also, the required operation of the feed pump to effect scavenging displaces the zone of conversion of liquid to vapor in coils not being scavenged with the result that the salt deposit zone may be shifted to an undesired part of the boiler. Accordingly, this arrangement for the removal of salt deposits from forced-flow boilers is objectionable, not only on account of the heat loss, but also on account of wandering of the salt deposit zone during cleaning periods. Therefore, it is a more specific object of my invention to provide the coils or tubular portions of the salt deposit zone of a forced-flow tubular boiler with means for injecting scavenging medium into the coils so that the salt deposits therein maybe dissolved, the solution being discharged through suitable outlet conduits.

These and other objects will be effected by my 10 invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. '1 is a vertical sectional view showing a 1 5 boiler incorporating my improvement; and

Figs. 2 to 11, inclusive, are diagrammatic views showing different arrangements of the scavenging apparatus;

In Fig. '1, I show a steam generator or boiler having heating spaces 5 6 and I through which heated gases flow in series from combustion apparatus, at 8, to the flue 9.

Heating surface elements are arranged in the heating spaces 5, -6 and "I, for example, as follows: element In in the space I; elements ll, l3 and I5 in the space 6 and elements l2 and M in the space 5.

Forced flow of operating medium, for example, water, is secured by means of a feed pump IS, the operating medium being supplied by the feed pump to the element l0 and passing from the latter in series through the elements ll, l2, l3, l4 and I5 and being discharged to the main I! as superheated steam.

The elements H), II, l2 and I3 are so designed and so distributed in the heating spaces that at least the final portion of evaporation is effected in the element I'3, that is, the arrangement and operation is such that the salt deposit 40 zone is normally confined to the element l3.

As shown, additions of heat are made to the operating medium by contact or convection in the sections 10 and l I, almost entirely radiantly in the section l2, and by contact in the element I3, theheat-additions being such that vaporization is effected in such a manner that the salt deposit zone is included in the section l3.

Steam is normally superheated to some extent before leaving the element 13, and it is further 5 superheated in the element I4, subject mainly to radiant heat, and in the element 5, subject mainly to contact heat.

The tubular elements II], II, |2, |3, I4 and I5 may be arranged in any suitable manner. For example, the element I6 is shown diagrammatically as being comprised by tubular portions or coils ;||la, ||]b,,and Inc, the tubular portions or coils being connected to the lnletheader lfld and the outlet header |0e. The other elements are shown diagrammatically in a similar manner,

the subscripts a, b, c, "d and e indicating similar parts and relations,

scavenging medium is supplied bythe conduits;

2|, 22 and 23 which are connected tothe tubular portions or coils |3a, |3b and I30, respectively, at the up-stream side of the salt-deposit zone, and it is discharged throughoutlet'conduits 24, 25 and 26 connected to the'.coils';|;3a, |*3b, I30, respectively, at the down-stream side of such zone.

262, respectively.

When it is desired to scavenge a tubular po'r i tion or .coil, for example, the tubular portion or coil |3a,.the valves 2|a and 24dareopened so that scavengingimedium maybe supplied through the conduit 2| todissolve deposits of salt'in the tubu-larelement. or coil 3a, the solution. being discharged through the conduit 24. -A throttling-or check valve device Ila, is arranged beyond thepoint of connection. of.-the discharge conduit 24 to prevent .substantialback flow from .theoutlet manifold |3e intothe coilbeing cleaned,

whereby loss of. heatedoperating 'medium is min imized. .In like .manner,-the coils |3liand |3care provided with back .fiow preventing. devices V I lb and He. As an additional medium isadmitted to scavengethe tubular elements, the-disadvantages .of heat loss andshiftingof the salt-deposit zone occasioned by the use of-the operatingme V ,dium for'thi's purposeareavoided. I

In Figs. 2 to 11, inclusive, there are shown diagrammatically different arrangementsoftubular elements and scavengingmeans therefor and corresponding to the tubular elements of the section |3 of Fig. 1. f

In-Fig. V 2, a pair .of parallel-connected tubular elements 30 are included in the boiler tubular-systern having the-feed pump .3: so that the. inlet ends 3| ofthe tubular-elements are supplied wit operating medium. M I

Each tubular element 30, has an inlet conduit 32forsupplyingscavenging medium thereto and has an-outlet conduit 33 for withdrawing scavengingfmedium and some of the operating -me diumtherefrom, theeconduits 32 and 33-having control valves 34 and 35, respectively.-.

Beyond the outlet conduit 33, eachtubular element 30 is provided with-a device; 36 forrestricting. backflow ofv operating medium into the out- .let conduit 33, whereby loss of operating medium '34"and 35of the associated conduits 32 and 33 The conduits 2|, 22,23, 24, 2,5 and 26 are... provided with valves 2|a, 22a,'23a, 24d, 25a; and

comprising parallel-connected tubular elements 4|;

The groups are so arranged with respect to the boiler tub'ularsy'stem that vaporizationis completed and salts deposit in the tubular elements 4| of the intermediate group. Each of the tubular elements 4| is provided with scavenging medium supply and withdrawal conduits 32 and 33 arranged and operating similarly to those of Fig. 2.

Fig. 4 shows a further modified arrangement.

of tubularelements wherein, instead of the intermediate group 42 being comprised by parallelconnected tubular elements as in Fig. 3, such intermediate group is comprised by sub-groups 43 and. 44,...each including parallel-connected tubularelements 45. vaporization of operating medium is completed and salt deposits occur in the tubular elements of the sub-groups.

With the arrangement of Fig. 4, it is possibl to scavengeall the tubular elements of a'subgroup. simultaneously. Accordingly, the subgroup 43 is provided'with-v a scavenging medium conduit 46 supplied by a pump; the conduit having aicontrol valve 48 and the conduit *46 is shown as being connected. to both of the tubular elements45 of the sub-group 43. The outlet conduit-49 is also connectedto both of thetubular elements- 45 of thesub-group 43. -With opening of the control-valves 48and- 50inthe conduits 46 and 49, the pump 41 is efiective to secure passage of scavenging medium in parallel-through the tubularelements of the sub-group 43;--- r a The sub-group 44 of Fig. 4 is arranged similarly to thesub-group 43 r and has a similar arrangement of scavenging medium supply and discharge conduits 46 and 43 the only difference being that, instead of the supply conduit 46 being furnished with scavenging medium by a: pump 41, such medium is supplied from a suitable'point in the-boiler system, 2 r y r In Figs. 5 to 11, inclusive, there are-shown scavenging arrangements including separating devices or traps 5|, which-serve to separate vapors and provide for continuance of flow of the latter in the boiler tubular system and minimize withdrawal thereof with the scavenging medium. The-traps or separating device 5| also serve'the purpose of the reverse-flow restricting'device 36 already described;

Referring to Fig. 5, the tubular element 52 includes a-section 53 containing the salt deposit zone; the section 53' discharging into theupper portion of the trap or separating device 5|. The trap or separating device has a vapor outlet 54 communicating wlith the upper portion thereof and-connected to the tubular portion55 of the boiler system; and the trap is also provided with a drainage outlet or conduit 56. scavenging medium is supplied through the conduit' 51 for passage through the tubulans'ecti'on 53' to dis solveand entrain salt deposits. With opening of the control valves 58 and 59 in the supply and drainage conduits 51 and 56,'respectively,'scavenging medium passes through the tubular secftion 53 along with operating medium and enters the upper portion of the trap: or separating devices 5|, the vapor separating from the liquid and passing through the outlet 54 for continued flow through the boiler tubular system and liquid with salts being drained from the bottom of the trap or receptacle through the conduit 56.

Fig. 6 shows an arrangement of parallel-connected tubular elements similar to Fig. 2 except that the salt deposit zones of the tubular elements have scavenging devices including traps 5 I.

Fig. 7 shows a pair of parallel-connected tubular elements each having salt deposit portions or zones 60 to which scavenge medium is supplied in parallel from the conduit 6| having the control valve 62. In like manner, the drainage conduit 63 is connected in parallel to the traps 5|, the drainage conduit having the control valve 64. With opening of the control valves 62 and 64, it will be apparent that the salt deposit sections 60 will be scavenged in parallel.

Fig. 8 shows an arrangement of parallel-connected salt deposit zone tubular elements 66 having scavenging medium supplied thereto in parallel from the conduit 61 having a control valve 68, the element 66 discharging into a single trap or separating device 5|.

Fig. 9 shows an arrangement similar in a general way to Fig. 3 except that the salt deposit tubular elements 69 of the intermediate group are, respectively, arranged to discharge into traps 5|.

Fig. 10 shows an arrangement similar to Fig. 9 except that scavenging medium is supplied by the conduits 10 for flow in parallel through the salt deposit zone tubular elements and such medium is withdrawn in parallel from the traps 5| by means of a drainage conduit 1|.

Fig. 11 shows a combination of the features of Figs. 8 and 10, scavenging medium being supplied by a conduit 12 for flow in parallel through the salt deposit zone tubular elements and being discharged with operating medium into a single trap 5|.

From the foregoing, it will be apparent that the tubular element or section l3, arranged in a convection heating space wherein temperatures normally prevail which are low enough to prevent injury to the tubing even though salt deposits occur within the walls thereof, may have a wide variety of mechanical arrangements; however, it is a characteristic feature that scavenging medium, in addition to the operating medium, is admitted at the up-stream side of the salt deposit zone portion of each tubular element, the scavenging medium being withdrawn from the tubular element at the down-stream side of the salt deposit zone. As it is desirable to minimize the loss of operating medium incident to scavenging, devices are provided to minimize the back-flow of operating medium through the tubular element and through the scavenging outlet during scavenging periods; and any suitable device may be employed for this purpose, for example, an orifice, reverse-flow restriction, valve or trap.

I claim as my invention: 7

1. In a steam generator of the once-through tubular type, a section comprising tubular means wherein completion of vaporization of operating medium is effected and salts deposit, apparatus for scavenging the salt deposit zone of said section including means for introducing water to the section at the up-stream side of the saltdeposit zone, said water being in addition to the operating medium supplied to the section, and means for discharging water with salts in solution and entrained thereby from the section at the down-stream side of the salt-deposit zone.

2. In a steam generator, a tubular system including a tubular element to the inlet end of which operating medium is supplied, within which evaporation of such medium is completed, and wherein salts deposit incident to evaporation; means for introducing scavenging medium to the tubular element beyond the inlet end thereof and at the up-stream side of the salt-deposit zone; and means for withdrawing scavenging medium from the tubular element at the down-stream side of the salt-deposit zone.

3. In a steam generator, a tubular system including a tubular element to the inlet end of which operating medium is supplied, within which evaporation of operating medium is completed, and wherein salts deposit incident to evaporation; means for introducing scavenging medium to the tubular element at the up-stream side of the salt deposit zone thereof; means for withdrawing scavenging medium from the tubular element at the downstream side of the salt-deposit zone; and means for restricting reverse flow of operating medium incident to scavenging.

4. In a steam generator, a tubular system including a plurality of tubular elements within which evaporation of operating medium is completed and wherein salts deposit incident to evaporation, means for introducing scavenging medium to each tubular element at the upstream side of the salt-deposit zone, means for withdrawing scavenging medium from each tubular element at the down-stream side of the saltdeposit zone, and means for controlling the scavenging medium admission and withdrawal means so that the tubular elements may be selectively scavenged.

5. In a steam generator, a tubular system including a plurality of parallel-connected tubular elements within which evaporation of operating medium is completed and wherein salts deposit incident to evaporation, conduit means for introducing scavenging medium to the tubular elements at the up-stream side of the salt-deposit zone thereof, conduit means for Withdrawing scavenging medium from said tubular elements at the down-stream side of the salt-deposit zone, and means for controlling the conduit means so that each tubular element may be scavenged.

6. In a steam generator, a tubular system including a plurality of tubular elements within which evaporation of operating medium is completed and wherein salts deposit incident to evaporation, conduits connected to the tubular elements for introducing scavenging medium thereto at the up-stream side of the salt-deposit zone, conduits connected to the tubular elements at the down-stream side of the salt-deposit zone for withdrawing scavenging medium, and valves arranged in the respective conduits for controlling scavenging operations.

7. In a steam generator, a tubular system including a tubular element within which evaporation of operating medium is completed and wherein salts deposit incident to evaporation, a conduit connected to the tubular element at the upstream side of the salt-deposit zone for introducing scavenging medium to the tubular element, a trap connected to the tubular element at the down-stream side of the salt-deposit zone, means providing a vapor outlet for said trap and constituting an element of said tubular system, a drainage outlet for the trap, and valves associated with said conduit and with the drainage outlet to control scavenging operations.

8. In a steam generator, a tubular system including a tubular element within which evaporation of operating medium is completed and wherein salts deposit incident to evaporation, means for introducing scavenging medium to said tubular element at the up-stream side of the salt deposit zone thereof, means providing a separa- 10 tion chamber into which said tubular element discharges, the discharge end of said tubular element being arranged at the down-"stream side of the salt-deposit zone, means providing a vapor outlet for said chamber and constituting an element of the tubular system, means providing a drainage outlet for the separation chamber, and valves for the scavenging medium admission means and the drainage outlet. 

